# Author:  James Tam
# Version: March, 2013

# Learning concepts:
# Pass by reference (passing a reference to a list)

# fun2(1DList)
# returns(1DList)
# Modify list 
# Return copy of reference back to caller
# fun1(): The return statement is not needed because the list 
# is passed by reference. (Passing ‘aListCopy’ as a parameter 
def fun1(aListCopy):
    aListCopy[0] = aListCopy[0] * 2
    aListCopy[1] = aListCopy[1] * 2
    return aListCopy

# Modify list
# Because aList copy refers to the list in 'start()' the return
# isn't needed
# fun2(1DList)
# returns(nothing)
# fun2(): a better programming convention is employed. The 
# approach taken in fun2() used be employed rather than the 
# one taken in fun1()
def fun2(aListCopy):
    aListCopy[0] = aListCopy[0] * 2
    aListCopy[1] = aListCopy[1] * 2

# start(none)
# returns(nothing)
def start():
    aList = [2,4]
    print("Original list in start() before function calls:\t", end="")
    print(aList)
    aList = fun1(aList)    
    print("Original list in start() after calling fun1():\t", end="")
    print(aList)
    fun2(aList)
    print("Original list in start() after calling fun2():\t", end="")
    print(aList)

start()